The short answer
Use fixed price when the scope is clear enough to write down — a logo, a five-page site, a defined report. Use hourly when the work is exploratory, ongoing, or will change as you go — debugging, consulting, open-ended design.
The rule cuts both ways. Fixed price on vague scope means the pro pads the quote or cuts corners. Hourly on a known deliverable means you’re funding someone else’s slow week. Match the model to how knowable the work is.
The real differences
| Hourly | Fixed price | |
|---|---|---|
| Who carries the risk | You (the buyer) | The provider |
| Best when scope is | Unknown or evolving | Defined up front |
| Budget certainty | Low — the meter runs | High — you know the number |
| Rewards efficiency | No — faster means less paid | Yes — faster means better margin |
| Scope changes | Absorbed easily | Need a change order |
| What you’re buying | Time and attention | A result |
Where each one wins
Hourly wins: discovery work, maintenance, advisory, and anything where you genuinely can’t specify the finish line yet. Cap it with a not-to-exceed number so the meter has a ceiling.
Fixed price wins: clearly defined deliverables where you want a firm budget and don’t care how long it takes. It pushes the risk of misestimation onto the person best placed to estimate — the pro.
The middle path
The pattern that keeps both sides honest: a small paid discovery phase (hourly), which produces a real scope, which becomes a fixed-price quote for the build. You buy certainty only once there’s something certain to price.
Whichever you choose, put it in writing — a statement of work defines what “done” means, and the freelance contract template has the billing terms built in. Sellers deciding what to charge can sanity-check with the freelance rate calculator.